Process of producing iron powder from cheap source material



1 profitable commercial use.

Patented Aug. 7, 1945 rnocsss or raonucnva mos rown mom CHEAP souncaua'raam John was, Cambridge, Mass.

No Drawing. Application May 29, 1942, Serial No. 445,084

4 Claims. (01. 75-28) This invention relates to a process of producingiron powder from cheap source material, more particularly to. producingiron powders from cheap reject ferruginous material, such as scrap shot.

As is known, in recent years there has been a marked extension in theuse of metal shot and powders for cleaning and cutting steel. Thesematerials include relatively cheap iron shot used for cleaning orblastingpurposes and more expensive products such as tungsten carbidepowder used for cutting metals.

In the use of cheaper iron shot, due to the high impact stresses, thematerial soon'fractures and powders. This powdered product, at thepresent time, has no substantial commercial market. A

- small amount is employed in the production of sparklcts but thegreater proportion constitutes a waste product.

The present invention comprehends the concept of utilizing such wastematerial as a source material for the production of fine metal powdersof essentially diiferent characteristics for which there is acommercialdemand, such as for fine blasting powders, for admixture withother metal powders in the production of powder compacts and the like.

The invention is based on the novel though in any suitable furnace so asto insure the formation of iron-carbon constituents, FeaC.

After carburization to the desired degree the material is then subjectedto magnetic separation in the manner described in my copendingapplication Serial No. 338,826, filed June 4, 1940. If desired prior tosuch separation the material may be disintegrated and/or classified soas to produce particles of the optimum particle size. By subjecting thematerial to magnetic separation the more magnetic constituents, such asvpearlite and the like are separated from the relatively non-magneticconstituents, such as iron carbide, graphite and the impurities, such assilicides and the like.

In this manner the impure waste material is converted to a more usefulform and is freed of undesirable impurities. After such separation, ifdesired, the cleaned product may be heat treated so as to produce thedesired metallurgical structure for the intended use.

The treated product, that is to say the screenings from the magneticseparator, serve as an simple concept that by a relatively simple metal-I lurgical trea ent, such waste or'reiect material may be converted intoa valuable commercial product.

The typical shot material which is employed for cleanin purposes isessentially a gray cast iron, 1. e. an iron-carbon alloy which isrelatively slowly cooled or quenched from the liquid phase such that thecarbon in the liquid system tends to come out as free graphite andgraphite eutectic. This material also contains a number of impurities,such as silicides and the like which while not especiallydisadvantageous in a cleaning shot is notdesirable for othermetallurgical According to the invention such waste or reject material,by suitable treatment, may be converted to a more valuable form whichfind a In one form of the invention the described waste material isprocessed to produce a fine cleaning shot. In carrying out the inventionthe waste material preferably is first cleaned of adherent oxide by anysuitable method, such as by pickling in a sulphuric acid pickle. Thecleaned and washed material is then carburized excellent fine cleaningpowder. This product, if desired may be mixed with reduced iron powderand utilized for the production of powder metal compacts. The improvedmethod thus provides an economical system of producing relatively highpriced products from scrap material.

While a preferred embodiment of the invention has been described it isto be understood that this is given-to exemplify the underlyingprinciples of the invention and not as limiting it to the particular onechosen for illustration.

I claim:

1. A method of producing iron powder from reject metal shot ofthe graycast iron type which comprisessubjecting the reject fines from said shotto a pickling operation toremove adherent oxides, washing the pickledmaterial, carburizing the cleaned product and subjecting the carburizedproduct to ma netic separation to recover the magnetic constituents.

2. A method of producing iron powder from reject metal shot of the graycast iron type material which comprises subiecting reject fines fromsaid shot to a pickling operation in a sulphuric acid solution, washingthe cleaned material, carburizing the product so as to insure theformation of iron-carbon constituents and magnetically separating therelative magnetic from the relatively non-magnetic constituents.

8. A method of producing iron powder from reject metal shot of the graycast iron type which comprises subjecting reject fines from said shottotheacflonotanflphuflcacidpickletoremovo adherent oxldea, wuhln: thepickled material, ;ca.rbm-1zln: the

product, clndtylnz the carbunledproducttoobtdn'ntmflonotthedaured meshmd sqblocflnz such'incflon to mumtlc thmatlon to recoverthe mam ticcomments erect. 4. A method at producing iron powder from reject metalshot of the In! cut'lron

